Web Application Basics.
What is Web Application?
Web Application is a Application software which runs on internet or can be consumed from internet.Web Application is a Application software designed, developed, deployed and consume using web.
What is Computer Network?
Computer Network is inter connection between two or more devices, to communicate / to exchange data.
e.g. WAN, LAN, MAN etc.
What is internet?
Internet is Forest of Networks (network or networks). In intial days in US, universities created their own LAN (local area network) in every department, then later on they interconnected all these departments,. After some universities decided to connect their networks to each otherw to communicate or exchange data. Later on govement organisation connected their networks, it happens over period and all the networks from all the countries get connected with each other that gives a birth to inetnert.
What is IP Address?
When every computer connect to network a unique address is assigned to that computer/device called IP Address. IP Address is basically unique numeric identifier of computer /devices connected to internet.
What is HTML?
HTML W3C standard called Hyper Text Markup Language , it is tag based or markup based technology which help to publish or shared data on internet.
Initially HTML is used only for publishing data on internet, later on new features get added in html, then we can format the data or create the presentation of data on web. Now days we can say html is used for web page designing.
What is HTTP?
Hyper text transfer protocol, this protocol allow you to exchange the html data or information using html documents (file which contains html tags). Similar to http we have ftp, smtp protocols. Http is state less stream based protocol.
What is Domain Name?
Domain is string name given to IP Address, you can create muliple domains in one computer identified by one IP Address.
What is Web Page?
Web Page is a html document , published on internet as a part of website can be accessed using domain name. New Features of HTML allow you to publish, format and design the content /data called web page designing.
What is Website?
What is ISP?
Internet service provide, there sare the companies who make their infrastructure available to us using which we can consume the internet/web.
What is DNS?
Domain name service , it will help you transalte domain name to ip address, for this dns will have a table which contains list of ipaddress and domain , it will search through that text file for domain and will get ip address of that domain.
What is OSI?
The Open Systems Interconnection model is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology. Every computer has network model, that model decides you to process your request. OSI one of the model. At the end request will reach to application layer.
How Internet Works?
Let us try to understand how internet works , to understand it refer the following diagram.
Step 1: First step we will open the web browser and type the url or website in address bar.
What is Web Browser?
Web browser is application software like google chrome, Microsoft edge, Firefox, Safari etc. which allow you to access the internet. Web browsers also interpret the tags from html document and generate the presentation of data in web browser body.
Step 2: Once you type the url e.g. http//www.ritechpune.com it will go to the device to which you had connected like hot spot, wifi device, lan and then your request go to your ISP (Internet Service Provider).
Step 3: ISP has a DNS service installed it will translate the domain name to IP Address and divert your request to the Specific Server Computer which has that IP Address.
What is DNS?
Domain Name service will translate the domain name to ip address, it maintain the list of domains and ip address for those domains.
Step 4: Once Request reaches to the RI-TECH Server it will go to OSI Model from OSI model it will travel towards the Application layer, in application layer we will have logical buffers those logical buffers are where request will be posted/ received called port.
What is Port?
So port is logical buffer in application layer of network model where the request for specific port will be received. Every port is identified by a unique no call port number and every port is assigned to specific protocol. e.g. HTTP port in general it will be 80/81.
Step 5:- Web Server is special application program installed on server computer who is responsible for scanning request at the HTTP port and process that request, if the request is just for some static file like html it will directly return it, if it is for some processing like if user sends emailed or password we need to check it for that a sever program will be invoked e.g. asp.net , PHP program. It will process request and generate html and send it to the user.
What is Web Server?
Web server is application software installed on a server computer, who is responsible for processing http requests. e.g. IIS (Internet Information Services), Apache, Tomcat, JBoss etc.
What is Client Side Scripting?
Client Side Scripting / Programming are the technologies which will help you to write some logic / code / program that will be executed in web browser (client side). Generally it is used to make html pages dynamic or add interactivity to Html pages or Documents.
What is Server Side Script/ Programming?
Server Side Scripting / Programming / Technologies allow you to write a logic to process the HTTP request in web server. Server Side Scripts/ Programming executes on server computer.
e.g. ASP.NET , PHP, JSP etc.